Grading and Excavation Contractor

Shielding for bore shafts and bridge piers

By Mike Fernandez

The Illinois Department of Transportation (IDOT) is upgrading water main pipelines that run underneath Chicago’s Dan Ryan Expressway as part of the $430 million five-year reconstruction project between 31st Street and the I-57 interchange. Bore shafts are being dug for crossings under the entire width of I-90/94 in specified areas which include 14-lane spans and railway tracks in the median for the Chicago Transit Authority’s (CTA’s) elevated subway trains known as the L. The I-90/94 reconstruction also includes an additional lane in each direction, a reconfigured skyway interchange, enhancements to adjacent local access roads, and improved sewers to solve drainage problems and reduce dangerous flooding on the expressway.

Photo: Efficiency Production

Kennedy crew swings Slide Rail panel onto corner post.

Joel Kennedy Construction from Waukegan, IL, is contracted to bore eight of the pipeline crossings that average 320 feet in length at an average depth of 32 feet. They are running 24-inch casings for 12-inch carrier pipe. The shafts are specified to be dug through paralleling surface roads and against 20-foot-tall retaining walls that border the expressway in order to have enough space to work in the limited areas between the walls and the expressway. The walls have to be braced and safe pits have to be maintained and prevented from collapsing. The tight digging spaces also prohibit the option of sloping the excavations. This challenging undertaking has a variety of risks such as the collapse of the roadway surface and tracks due to vibrations from the excavation and boring equipment and the displacement of soil; the integrity of the retaining walls that border the expressway must also be maintained.

After careful consideration, Kennedy has chosen to rent an Efficiency Production Inc. four-sided Slide Rail System measuring 16- by 16-foot square by 32-feet deep to shield the bore pits that are specified at various depths dependent on their location along the expressway. The versatile system can also be used for a 16- by 12-foot-wide pit. This shielding process limits the amount of vibration normally associated with sheet piling since it does not have to be driven with such force. Since the Efficiency Slide Rail is a dig and push system, Kennedy is able to excavate the pit and install the shielding simultaneously, which saves a significant amount of time and money by digging vertical pit walls down to grade rather than sloping the excavation or digging out the entire pit at once, risking the collapse of unshored pit walls, bordering retaining walls, and the surface roads. Making narrower cuts also reduces the amount of material to dig, transport, backfill, and restore. By using the Slide Rail System, Kennedy can safely achieve the required depth within feet of the roads, the walls, and existing utilities.

After temporary bracing for the retaining walls are in place, Slide Rail corner posts are installed adjacent to the wall footings just far enough away to anticipate the amount of taper at the footing depth. Then each side of the first level of 8-foot-tall by 16-foot-long panels and the remaining posts are positioned to lay out the square pit and then pushed down in manageable increments at each corner to keep the system square and the post and panel binding minimized. Then, similarly, the next two levels of panels are installed and pushed to grade to complete the square pit shield. Kennedy’s Crew Leader Bernie Prisby states, “The system worked great up to 25 feet,” where the crew encountered extremely dense clay, but the durable Slide Rail components withstood the pressure of the final push down to 32 feet. System Installer Kelly Wilson notes, “The Slide Rail has worked very well. For instance, in one of the pits we were able to overcome abandoned sheeting left over from previous construction by lifting a panel above the obstruction within OSHA regulations and without compromising the rest of the system.”

I-80 Bridge Construction
IDOT is also reconstructing the Robert Kingery Expressway (I-80/94) from the Illinois-Indiana border west 6.6 miles to the I-80 and I-94/IL394 interchange south of Chicago near Lansing, IL. The $300 million project includes widening and adding lanes in each direction, road resurfacing and improvements to local access roads, installation of high-mast tower lighting, building of retaining and sound walls to reduce expressway noise in residential areas, addition of guardrails and barrier walls, and bridge replacements.

Photo: Efficiency Production

Bridge replacement in tight quarters on Illinois's I-80

James Cape & Sons Co. from Racine, WI, is working on several bridge piers along this stretch of expressway where 160,000 vehicles travel per day. Night construction and lane closures for pier footing excavations and erecting bridge beams have been necessary, but working space is still extremely limited and congested. Pier footings are being set at 12-foot depths inside of 24-foot-wide pits in the center and the sides of the expressway.

Cape’s Site Superintendent Jeff Meaghercontacted Joe Ott of United Rentals in Villa Park, IL, to discuss shielding options for this project since they have rented roadwork equipment from Ott’s Highway Technology department and knew that his Villa Park branch had a Trench Safety division. Ott corresponded with Efficiency Production’s Director of Engineering Mike West to determine the best approach for the job. Project specifications were drawn and a consensus was reached to use two 22- by 22-foot square by 12-foot-deep Efficiency Production Slide Rail Systems rented through United Rentals.

The old road surface is torn out first. Then the excavation begins while placing the Slide Rail posts and panels into position, carefully swinging the components within the limited space while avoiding all oncoming traffic and other obstructions. Cape’s crews continue digging the pits and pushing down the shielding systems with a Link-Belt 460LX excavator until the 12-foot depths are reached. When the pits are safely shielded, the footings are poured, and the piers are set, then the Slide Rail components are removed before the bridge beams are erected.

At the time of this writing, the bridgework was on schedule and different locations were projected for completion from October 31, 2004, through October 30, 2005.

Mike Fernandez writes for Efficiency Production Inc. at Mason, MI.

GEC - January/February 2007

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